I once went to an amazing two hour talk on this and all the hidden meanings, it was something, he really made a good case for Paul dying and being replaced.
Back ward masking, album covers etc., etc.,
Of course I spent months trying to debunk all he presented, he was a colleague so finally I just asked him if it was true and he said no, it was all John Lennon being sardonic.
What a waste of my time. lol